Sorry I was wrong on that point, but from what I’ve seen with some friends (and not even the stricter Amish, but Mennonite), while there might not be an outright bann or shunning, the young people who do not choose to join the community in baptism are treated “politely”, more like friends than family. The friend in question left home before she was baptized, met and married a young man from a different Christian faith (and different ethnic background) and while her family did attend the wedding (as did we), they were quite standoffish, even with their own daughter/sister. Mom did melt a bit when her daughter walked down the aisle, but she looked more like someone who was waiting to have dental work done than a proud or happy mother-of-the-bride (of course, I don’t know what a Mennonite wedding would be like, so maybe she was just uncomfortable with the whole thing.) Our friend has said that visits to her sisters and their families are “cordial” and short… she and her husband feel as if her family is afraid of their being a “bad influence” on the other young members of their households.
So while there is no “actual” bann or shunning of unbaptized family members, from what I’ve seen, my friend feels as if the road home has been closed almost as if she had been shunned. I’m sure that’s not true of all families, but it happens maybe more than is let on to outsiders.